The Core B Bioassay Core is designed to serve the Research Base as a centralized resource for preparation and storage of clinical samples, and for conducting a range of basic science assays on clinically derived material. In the less than two years since its founding, the Bioassay Core has already proven its ability to serve the members of the Division of Rheumatology, by providing crucial assay services for two peerreviewed publications, several abstracts accepted for presentation at the American College of Rheumatology, and three recently submitted investigator-initiated grant proposals. The aim of this proposal is to build from this strong beginning, providing a wider array of services to a larger number of investigators inside and outside the Division, investigating the causes, diagnosis, and treatment of autoimmune rheumatic disease. While both basic scienctists and clinicians have historically excelled in the Division, in recent years the Division has witnessed a leap forward in clinical research, through the establishment of the clinical Centers of Excellence in SLE, scleroderma, inflammatory arthritis, vasculitis, and most recently myositis. The next leap forward will require the same central coordination of human and physical resources on the basic science side, and the Bioassay Core represents a critical step in that direction. The Bioassay Core will provide the following services: sample preparation and storage, including RNA and DNA preparation from whole blood and PBMC preparation and cryopreservation;analysis of soluble molecules using ELISA and multiparameter bead-based assays;flow cytometry;immunohistochemistry;and autoantibodies and other immunological assays. The Core will be led by Dr. James Mahoney, who has managed the Core since its inception and has many years experience in immunology and assay development. Additional leadership will be provided by Drs. Mark Soloski and Livia Casciola-Rosen. The functions of the Bioassay Core will provide critical synergies with the Genomics/Genotyping Core and the clinical Centers of Excellence, and will provide a fertile environment for the next generation of discoveries in the autoimmune rheumatic diseases.